mm/numa_emulation.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * NUMA emulation
  */
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/topology.h>
 #include <linux/memblock.h>
 #include <linux/numa_memblks.h>
 #include <asm/numa.h>

 #define FAKE_NODE_MIN_SIZE	((u64)32 << 20)
 #define FAKE_NODE_MIN_HASH_MASK	(~(FAKE_NODE_MIN_SIZE - 1UL))

 static int emu_nid_to_phys[MAX_NUMNODES];
 static char *emu_cmdline __initdata;

 int __init numa_emu_cmdline(char *str)
 {
 	emu_cmdline = str;
 	return 0;
 }

 static int __init emu_find_memblk_by_nid(int nid, const struct numa_meminfo *mi)
 {
 	int i;

 	for (i = 0; i < mi->nr_blks; i++)
 		if (mi->blk[i].nid == nid)
 			return i;
 	return -ENOENT;
 }

 static u64 __init mem_hole_size(u64 start, u64 end)
 {
 	unsigned long start_pfn = PFN_UP(start);
 	unsigned long end_pfn = PFN_DOWN(end);

 	if (start_pfn < end_pfn)
 		return PFN_PHYS(absent_pages_in_range(start_pfn, end_pfn));
 	return 0;
 }

 /*
  * Sets up nid to range from @start to @end.  The return value is -errno if
  * something went wrong, 0 otherwise.
  */
 static int __init emu_setup_memblk(struct numa_meminfo *ei,
 				   struct numa_meminfo *pi,
 				   int nid, int phys_blk, u64 size)
 {
 	struct numa_memblk *eb = &ei->blk[ei->nr_blks];
 	struct numa_memblk *pb = &pi->blk[phys_blk];

 	if (ei->nr_blks >= NR_NODE_MEMBLKS) {
 		pr_err("NUMA: Too many emulated memblks, failing emulation\n");
 		return -EINVAL;
 	}

 	ei->nr_blks++;
 	eb->start = pb->start;
 	eb->end = pb->start + size;
 	eb->nid = nid;

 	if (emu_nid_to_phys[nid] == NUMA_NO_NODE)
 		emu_nid_to_phys[nid] = pb->nid;

 	pb->start += size;
 	if (pb->start >= pb->end) {
 		WARN_ON_ONCE(pb->start > pb->end);
 		numa_remove_memblk_from(phys_blk, pi);
 	}

 	printk(KERN_INFO "Faking node %d at [mem %#018Lx-%#018Lx] (%LuMB)\n",
 	       nid, eb->start, eb->end - 1, (eb->end - eb->start) >> 20);
 	return 0;
 }

 /*
  * Sets up nr_nodes fake nodes interleaved over physical nodes ranging from addr
  * to max_addr.
  *
  * Returns zero on success or negative on error.
  */
 static int __init split_nodes_interleave(struct numa_meminfo *ei,
 					 struct numa_meminfo *pi,
 					 u64 addr, u64 max_addr, int nr_nodes)
 {
 	nodemask_t physnode_mask = numa_nodes_parsed;
 	u64 size;
 	int big;
 	int nid = 0;
 	int i, ret;

 	if (nr_nodes <= 0)
 		return -1;
 	if (nr_nodes > MAX_NUMNODES) {
 		pr_info("numa=fake=%d too large, reducing to %d\n",
 			nr_nodes, MAX_NUMNODES);
 		nr_nodes = MAX_NUMNODES;
 	}

 	/*
 	 * Calculate target node size.  x86_32 freaks on __udivdi3() so do
 	 * the division in ulong number of pages and convert back.
 	 */
 	size = max_addr - addr - mem_hole_size(addr, max_addr);
 	size = PFN_PHYS((unsigned long)(size >> PAGE_SHIFT) / nr_nodes);

 	/*
 	 * Calculate the number of big nodes that can be allocated as a result
 	 * of consolidating the remainder.
 	 */
 	big = ((size & ~FAKE_NODE_MIN_HASH_MASK) * nr_nodes) /
 		FAKE_NODE_MIN_SIZE;

 	size &= FAKE_NODE_MIN_HASH_MASK;
 	if (!size) {
 		pr_err("Not enough memory for each node.  "
 			"NUMA emulation disabled.\n");
 		return -1;
 	}

 	/*
 	 * Continue to fill physical nodes with fake nodes until there is no
 	 * memory left on any of them.
 	 */
 	while (!nodes_empty(physnode_mask)) {
 		for_each_node_mask(i, physnode_mask) {
 			u64 dma32_end = numa_emu_dma_end();
 			u64 start, limit, end;
 			int phys_blk;

 			phys_blk = emu_find_memblk_by_nid(i, pi);
 			if (phys_blk < 0) {
 				node_clear(i, physnode_mask);
 				continue;
 			}
 			start = pi->blk[phys_blk].start;
 			limit = pi->blk[phys_blk].end;
 			end = start + size;

 			if (nid < big)
 				end += FAKE_NODE_MIN_SIZE;

 			/*
 			 * Continue to add memory to this fake node if its
 			 * non-reserved memory is less than the per-node size.
 			 */
 			while (end - start - mem_hole_size(start, end) < size) {
 				end += FAKE_NODE_MIN_SIZE;
 				if (end > limit) {
 					end = limit;
 					break;
 				}
 			}

 			/*
 			 * If there won't be at least FAKE_NODE_MIN_SIZE of
 			 * non-reserved memory in ZONE_DMA32 for the next node,
 			 * this one must extend to the boundary.
 			 */
 			if (end < dma32_end && dma32_end - end -
 			    mem_hole_size(end, dma32_end) < FAKE_NODE_MIN_SIZE)
 				end = dma32_end;

 			/*
 			 * If there won't be enough non-reserved memory for the
 			 * next node, this one must extend to the end of the
 			 * physical node.
 			 */
 			if (limit - end - mem_hole_size(end, limit) < size)
 				end = limit;

 			ret = emu_setup_memblk(ei, pi, nid++ % nr_nodes,
 					       phys_blk,
 					       min(end, limit) - start);
 			if (ret < 0)
 				return ret;
 		}
 	}
 	return 0;
 }

 /*
  * Returns the end address of a node so that there is at least `size' amount of
  * non-reserved memory or `max_addr' is reached.
  */
 static u64 __init find_end_of_node(u64 start, u64 max_addr, u64 size)
 {
 	u64 end = start + size;

 	while (end - start - mem_hole_size(start, end) < size) {
 		end += FAKE_NODE_MIN_SIZE;
 		if (end > max_addr) {
 			end = max_addr;
 			break;
 		}
 	}
 	return end;
 }

 static u64 uniform_size(u64 max_addr, u64 base, u64 hole, int nr_nodes)
 {
 	unsigned long max_pfn = PHYS_PFN(max_addr);
 	unsigned long base_pfn = PHYS_PFN(base);
 	unsigned long hole_pfns = PHYS_PFN(hole);

 	return PFN_PHYS((max_pfn - base_pfn - hole_pfns) / nr_nodes);
 }

 /*
  * Sets up fake nodes of `size' interleaved over physical nodes ranging from
  * `addr' to `max_addr'.
  *
  * Returns zero on success or negative on error.
  */
 static int __init split_nodes_size_interleave_uniform(struct numa_meminfo *ei,
 					      struct numa_meminfo *pi,
 					      u64 addr, u64 max_addr, u64 size,
 					      int nr_nodes, struct numa_memblk *pblk,
 					      int nid)
 {
 	nodemask_t physnode_mask = numa_nodes_parsed;
 	int i, ret, uniform = 0;
 	u64 min_size;

 	if ((!size && !nr_nodes) || (nr_nodes && !pblk))
 		return -1;

 	/*
 	 * In the 'uniform' case split the passed in physical node by
 	 * nr_nodes, in the non-uniform case, ignore the passed in
 	 * physical block and try to create nodes of at least size
 	 * @size.
 	 *
 	 * In the uniform case, split the nodes strictly by physical
 	 * capacity, i.e. ignore holes. In the non-uniform case account
 	 * for holes and treat @size as a minimum floor.
 	 */
 	if (!nr_nodes)
 		nr_nodes = MAX_NUMNODES;
 	else {
 		nodes_clear(physnode_mask);
 		node_set(pblk->nid, physnode_mask);
 		uniform = 1;
 	}

 	if (uniform) {
 		min_size = uniform_size(max_addr, addr, 0, nr_nodes);
 		size = min_size;
 	} else {
 		/*
 		 * The limit on emulated nodes is MAX_NUMNODES, so the
 		 * size per node is increased accordingly if the
 		 * requested size is too small.  This creates a uniform
 		 * distribution of node sizes across the entire machine
 		 * (but not necessarily over physical nodes).
 		 */
 		min_size = uniform_size(max_addr, addr,
 				mem_hole_size(addr, max_addr), nr_nodes);
 	}
 	min_size = ALIGN(max(min_size, FAKE_NODE_MIN_SIZE), FAKE_NODE_MIN_SIZE);
 	if (size < min_size) {
 		pr_err("Fake node size %LuMB too small, increasing to %LuMB\n",
 			size >> 20, min_size >> 20);
 		size = min_size;
 	}
 	size = ALIGN_DOWN(size, FAKE_NODE_MIN_SIZE);

 	/*
 	 * Fill physical nodes with fake nodes of size until there is no memory
 	 * left on any of them.
 	 */
 	while (!nodes_empty(physnode_mask)) {
 		for_each_node_mask(i, physnode_mask) {
 			u64 dma32_end = numa_emu_dma_end();
 			u64 start, limit, end;
 			int phys_blk;

 			phys_blk = emu_find_memblk_by_nid(i, pi);
 			if (phys_blk < 0) {
 				node_clear(i, physnode_mask);
 				continue;
 			}

 			start = pi->blk[phys_blk].start;
 			limit = pi->blk[phys_blk].end;

 			if (uniform)
 				end = start + size;
 			else
 				end = find_end_of_node(start, limit, size);
 			/*
 			 * If there won't be at least FAKE_NODE_MIN_SIZE of
 			 * non-reserved memory in ZONE_DMA32 for the next node,
 			 * this one must extend to the boundary.
 			 */
 			if (end < dma32_end && dma32_end - end -
 			    mem_hole_size(end, dma32_end) < FAKE_NODE_MIN_SIZE)
 				end = dma32_end;

 			/*
 			 * If there won't be enough non-reserved memory for the
 			 * next node, this one must extend to the end of the
 			 * physical node.
 			 */
 			if ((limit - end - mem_hole_size(end, limit) < size)
 					&& !uniform)
 				end = limit;

 			ret = emu_setup_memblk(ei, pi, nid++ % MAX_NUMNODES,
 					       phys_blk,
 					       min(end, limit) - start);
 			if (ret < 0)
 				return ret;
 		}
 	}
 	return nid;
 }

 static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
 					      struct numa_meminfo *pi,
 					      u64 addr, u64 max_addr, u64 size)
 {
 	return split_nodes_size_interleave_uniform(ei, pi, addr, max_addr, size,
 			0, NULL, 0);
 }

 static int __init setup_emu2phys_nid(int *dfl_phys_nid)
 {
 	int i, max_emu_nid = 0;

 	*dfl_phys_nid = NUMA_NO_NODE;
 	for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++) {
 		if (emu_nid_to_phys[i] != NUMA_NO_NODE) {
 			max_emu_nid = i;
 			if (*dfl_phys_nid == NUMA_NO_NODE)
 				*dfl_phys_nid = emu_nid_to_phys[i];
 		}
 	}

 	return max_emu_nid;
 }

 /**
  * numa_emulation - Emulate NUMA nodes
  * @numa_meminfo: NUMA configuration to massage
  * @numa_dist_cnt: The size of the physical NUMA distance table
  *
  * Emulate NUMA nodes according to the numa=fake kernel parameter.
  * @numa_meminfo contains the physical memory configuration and is modified
  * to reflect the emulated configuration on success.  @numa_dist_cnt is
  * used to determine the size of the physical distance table.
  *
  * On success, the following modifications are made.
  *
  * - @numa_meminfo is updated to reflect the emulated nodes.
  *
  * - __apicid_to_node[] is updated such that APIC IDs are mapped to the
  *   emulated nodes.
  *
  * - NUMA distance table is rebuilt to represent distances between emulated
  *   nodes.  The distances are determined considering how emulated nodes
  *   are mapped to physical nodes and match the actual distances.
  *
  * - emu_nid_to_phys[] reflects how emulated nodes are mapped to physical
  *   nodes.  This is used by numa_add_cpu() and numa_remove_cpu().
  *
  * If emulation is not enabled or fails, emu_nid_to_phys[] is filled with
  * identity mapping and no other modification is made.
  */
 void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
 {
 	static struct numa_meminfo ei __initdata;
 	static struct numa_meminfo pi __initdata;
 	const u64 max_addr = PFN_PHYS(max_pfn);
 	u8 *phys_dist = NULL;
 	size_t phys_size = numa_dist_cnt * numa_dist_cnt * sizeof(phys_dist[0]);
 	int max_emu_nid, dfl_phys_nid;
 	int i, j, ret;

 	if (!emu_cmdline)
 		goto no_emu;

 	memset(&ei, 0, sizeof(ei));
 	pi = *numa_meminfo;

 	for (i = 0; i < MAX_NUMNODES; i++)
 		emu_nid_to_phys[i] = NUMA_NO_NODE;

 	/*
 	 * If the numa=fake command-line contains a 'M' or 'G', it represents
 	 * the fixed node size.  Otherwise, if it is just a single number N,
 	 * split the system RAM into N fake nodes.
 	 */
 	if (strchr(emu_cmdline, 'U')) {
 		nodemask_t physnode_mask = numa_nodes_parsed;
 		unsigned long n;
 		int nid = 0;

 		n = simple_strtoul(emu_cmdline, &emu_cmdline, 0);
 		ret = -1;
 		for_each_node_mask(i, physnode_mask) {
 			/*
 			 * The reason we pass in blk[0] is due to
 			 * numa_remove_memblk_from() called by
 			 * emu_setup_memblk() will delete entry 0
 			 * and then move everything else up in the pi.blk
 			 * array. Therefore we should always be looking
 			 * at blk[0].
 			 */
 			ret = split_nodes_size_interleave_uniform(&ei, &pi,
 					pi.blk[0].start, pi.blk[0].end, 0,
 					n, &pi.blk[0], nid);
 			if (ret < 0)
 				break;
 			if (ret < n) {
 				pr_info("%s: phys: %d only got %d of %ld nodes, failing\n",
 						__func__, i, ret, n);
 				ret = -1;
 				break;
 			}
 			nid = ret;
 		}
 	} else if (strchr(emu_cmdline, 'M') || strchr(emu_cmdline, 'G')) {
 		u64 size;

 		size = memparse(emu_cmdline, &emu_cmdline);
 		ret = split_nodes_size_interleave(&ei, &pi, 0, max_addr, size);
 	} else {
 		unsigned long n;

 		n = simple_strtoul(emu_cmdline, &emu_cmdline, 0);
 		ret = split_nodes_interleave(&ei, &pi, 0, max_addr, n);
 	}
 	if (*emu_cmdline == ':')
 		emu_cmdline++;

 	if (ret < 0)
 		goto no_emu;

 	if (numa_cleanup_meminfo(&ei) < 0) {
 		pr_warn("NUMA: Warning: constructed meminfo invalid, disabling emulation\n");
 		goto no_emu;
 	}

 	/* copy the physical distance table */
 	if (numa_dist_cnt) {
 		phys_dist = memblock_alloc(phys_size, PAGE_SIZE);
 		if (!phys_dist) {
 			pr_warn("NUMA: Warning: can't allocate copy of distance table, disabling emulation\n");
 			goto no_emu;
 		}

 		for (i = 0; i < numa_dist_cnt; i++)
 			for (j = 0; j < numa_dist_cnt; j++)
 				phys_dist[i * numa_dist_cnt + j] =
 					node_distance(i, j);
 	}

 	/*
 	 * Determine the max emulated nid and the default phys nid to use
 	 * for unmapped nodes.
 	 */
 	max_emu_nid = setup_emu2phys_nid(&dfl_phys_nid);

 	/* commit */
 	*numa_meminfo = ei;

 	/* Make sure numa_nodes_parsed only contains emulated nodes */
 	nodes_clear(numa_nodes_parsed);
 	for (i = 0; i < ARRAY_SIZE(ei.blk); i++)
 		if (ei.blk[i].start != ei.blk[i].end &&
 		    ei.blk[i].nid != NUMA_NO_NODE)
 			node_set(ei.blk[i].nid, numa_nodes_parsed);

 	numa_emu_update_cpu_to_node(emu_nid_to_phys, ARRAY_SIZE(emu_nid_to_phys));

 	/* make sure all emulated nodes are mapped to a physical node */
 	for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++)
 		if (emu_nid_to_phys[i] == NUMA_NO_NODE)
 			emu_nid_to_phys[i] = dfl_phys_nid;

 	/* transform distance table */
 	numa_reset_distance();
 	for (i = 0; i < max_emu_nid + 1; i++) {
 		for (j = 0; j < max_emu_nid + 1; j++) {
 			int physi = emu_nid_to_phys[i];
 			int physj = emu_nid_to_phys[j];
 			int dist;

 			if (get_option(&emu_cmdline, &dist) == 2)
 				;
 			else if (physi >= numa_dist_cnt || physj >= numa_dist_cnt)
 				dist = physi == physj ?
 					LOCAL_DISTANCE : REMOTE_DISTANCE;
 			else
 				dist = phys_dist[physi * numa_dist_cnt + physj];

 			numa_set_distance(i, j, dist);
 		}
 	}

 	/* free the copied physical distance table */
 	memblock_free(phys_dist, phys_size);
 	return;

 no_emu:
 	/* No emulation.  Build identity emu_nid_to_phys[] for numa_add_cpu() */
 	for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++)
 		emu_nid_to_phys[i] = i;
 }

 #ifndef CONFIG_DEBUG_PER_CPU_MAPS
 void numa_add_cpu(unsigned int cpu)
 {
 	int physnid, nid;

 	nid = early_cpu_to_node(cpu);
 	BUG_ON(nid == NUMA_NO_NODE || !node_online(nid));

 	physnid = emu_nid_to_phys[nid];

 	/*
 	 * Map the cpu to each emulated node that is allocated on the physical
 	 * node of the cpu's apic id.
 	 */
 	for_each_online_node(nid)
 		if (emu_nid_to_phys[nid] == physnid)
 			cpumask_set_cpu(cpu, node_to_cpumask_map[nid]);
 }

 void numa_remove_cpu(unsigned int cpu)
 {
 	int i;

 	for_each_online_node(i)
 		cpumask_clear_cpu(cpu, node_to_cpumask_map[i]);
 }
 #else	/* !CONFIG_DEBUG_PER_CPU_MAPS */
 static void numa_set_cpumask(unsigned int cpu, bool enable)
 {
 	int nid, physnid;

 	nid = early_cpu_to_node(cpu);
 	if (nid == NUMA_NO_NODE) {
 		/* early_cpu_to_node() already emits a warning and trace */
 		return;
 	}

 	physnid = emu_nid_to_phys[nid];

 	for_each_online_node(nid) {
 		if (emu_nid_to_phys[nid] != physnid)
 			continue;

 		debug_cpumask_set_cpu(cpu, nid, enable);
 	}
 }

 void numa_add_cpu(unsigned int cpu)
 {
 	numa_set_cpumask(cpu, true);
 }

 void numa_remove_cpu(unsigned int cpu)
 {
 	numa_set_cpumask(cpu, false);
 }
 #endif	/* !CONFIG_DEBUG_PER_CPU_MAPS */
	// SPDX-License-Identifier: GPL-2.0
	/*
	* NUMA emulation
	*/
	#include <linux/kernel.h>
	#include <linux/errno.h>
	#include <linux/topology.h>
	#include <linux/memblock.h>
	#include <linux/numa_memblks.h>
	#include <asm/numa.h>

	#define FAKE_NODE_MIN_SIZE ((u64)32 << 20)
	#define FAKE_NODE_MIN_HASH_MASK (~(FAKE_NODE_MIN_SIZE - 1UL))

	static int emu_nid_to_phys[MAX_NUMNODES];
	static char *emu_cmdline __initdata;

	int __init numa_emu_cmdline(char *str)
	{
	emu_cmdline = str;
	return 0;
	}

	static int __init emu_find_memblk_by_nid(int nid, const struct numa_meminfo *mi)
	{
	int i;

	for (i = 0; i < mi->nr_blks; i++)
	if (mi->blk[i].nid == nid)
	return i;
	return -ENOENT;
	}

	static u64 __init mem_hole_size(u64 start, u64 end)
	{
	unsigned long start_pfn = PFN_UP(start);
	unsigned long end_pfn = PFN_DOWN(end);

	if (start_pfn < end_pfn)
	return PFN_PHYS(absent_pages_in_range(start_pfn, end_pfn));
	return 0;
	}

	/*
	* Sets up nid to range from @start to @end. The return value is -errno if
	* something went wrong, 0 otherwise.
	*/
	static int __init emu_setup_memblk(struct numa_meminfo *ei,
	struct numa_meminfo *pi,
	int nid, int phys_blk, u64 size)
	{
	struct numa_memblk *eb = &ei->blk[ei->nr_blks];
	struct numa_memblk *pb = &pi->blk[phys_blk];

	if (ei->nr_blks >= NR_NODE_MEMBLKS) {
	pr_err("NUMA: Too many emulated memblks, failing emulation\n");
	return -EINVAL;
	}

	ei->nr_blks++;
	eb->start = pb->start;
	eb->end = pb->start + size;
	eb->nid = nid;

	if (emu_nid_to_phys[nid] == NUMA_NO_NODE)
	emu_nid_to_phys[nid] = pb->nid;

	pb->start += size;
	if (pb->start >= pb->end) {
	WARN_ON_ONCE(pb->start > pb->end);
	numa_remove_memblk_from(phys_blk, pi);
	}

	printk(KERN_INFO "Faking node %d at [mem %#018Lx-%#018Lx] (%LuMB)\n",
	nid, eb->start, eb->end - 1, (eb->end - eb->start) >> 20);
	return 0;
	}

	/*
	* Sets up nr_nodes fake nodes interleaved over physical nodes ranging from addr
	* to max_addr.
	*
	* Returns zero on success or negative on error.
	*/
	static int __init split_nodes_interleave(struct numa_meminfo *ei,
	struct numa_meminfo *pi,
	u64 addr, u64 max_addr, int nr_nodes)
	{
	nodemask_t physnode_mask = numa_nodes_parsed;
	u64 size;
	int big;
	int nid = 0;
	int i, ret;

	if (nr_nodes <= 0)
	return -1;
	if (nr_nodes > MAX_NUMNODES) {
	pr_info("numa=fake=%d too large, reducing to %d\n",
	nr_nodes, MAX_NUMNODES);
	nr_nodes = MAX_NUMNODES;
	}

	/*
	* Calculate target node size. x86_32 freaks on __udivdi3() so do
	* the division in ulong number of pages and convert back.
	*/
	size = max_addr - addr - mem_hole_size(addr, max_addr);
	size = PFN_PHYS((unsigned long)(size >> PAGE_SHIFT) / nr_nodes);

	/*
	* Calculate the number of big nodes that can be allocated as a result
	* of consolidating the remainder.
	*/
	big = ((size & ~FAKE_NODE_MIN_HASH_MASK) * nr_nodes) /
	FAKE_NODE_MIN_SIZE;

	size &= FAKE_NODE_MIN_HASH_MASK;
	if (!size) {
	pr_err("Not enough memory for each node. "
	"NUMA emulation disabled.\n");
	return -1;
	}

	/*
	* Continue to fill physical nodes with fake nodes until there is no
	* memory left on any of them.
	*/
	while (!nodes_empty(physnode_mask)) {
	for_each_node_mask(i, physnode_mask) {
	u64 dma32_end = numa_emu_dma_end();
	u64 start, limit, end;
	int phys_blk;

	phys_blk = emu_find_memblk_by_nid(i, pi);
	if (phys_blk < 0) {
	node_clear(i, physnode_mask);
	continue;
	}
	start = pi->blk[phys_blk].start;
	limit = pi->blk[phys_blk].end;
	end = start + size;

	if (nid < big)
	end += FAKE_NODE_MIN_SIZE;

	/*
	* Continue to add memory to this fake node if its
	* non-reserved memory is less than the per-node size.
	*/
	while (end - start - mem_hole_size(start, end) < size) {
	end += FAKE_NODE_MIN_SIZE;
	if (end > limit) {
	end = limit;
	break;
	}
	}

	/*
	* If there won't be at least FAKE_NODE_MIN_SIZE of
	* non-reserved memory in ZONE_DMA32 for the next node,
	* this one must extend to the boundary.
	*/
	if (end < dma32_end && dma32_end - end -
	mem_hole_size(end, dma32_end) < FAKE_NODE_MIN_SIZE)
	end = dma32_end;

	/*
	* If there won't be enough non-reserved memory for the
	* next node, this one must extend to the end of the
	* physical node.
	*/
	if (limit - end - mem_hole_size(end, limit) < size)
	end = limit;

	ret = emu_setup_memblk(ei, pi, nid++ % nr_nodes,
	phys_blk,
	min(end, limit) - start);
	if (ret < 0)
	return ret;
	}
	}
	return 0;
	}

	/*
	* Returns the end address of a node so that there is at least `size' amount of
	* non-reserved memory or `max_addr' is reached.
	*/
	static u64 __init find_end_of_node(u64 start, u64 max_addr, u64 size)
	{
	u64 end = start + size;

	while (end - start - mem_hole_size(start, end) < size) {
	end += FAKE_NODE_MIN_SIZE;
	if (end > max_addr) {
	end = max_addr;
	break;
	}
	}
	return end;
	}

	static u64 uniform_size(u64 max_addr, u64 base, u64 hole, int nr_nodes)
	{
	unsigned long max_pfn = PHYS_PFN(max_addr);
	unsigned long base_pfn = PHYS_PFN(base);
	unsigned long hole_pfns = PHYS_PFN(hole);

	return PFN_PHYS((max_pfn - base_pfn - hole_pfns) / nr_nodes);
	}

	/*
	* Sets up fake nodes of `size' interleaved over physical nodes ranging from
	* `addr' to `max_addr'.
	*
	* Returns zero on success or negative on error.
	*/
	static int __init split_nodes_size_interleave_uniform(struct numa_meminfo *ei,
	struct numa_meminfo *pi,
	u64 addr, u64 max_addr, u64 size,
	int nr_nodes, struct numa_memblk *pblk,
	int nid)
	{
	nodemask_t physnode_mask = numa_nodes_parsed;
	int i, ret, uniform = 0;
	u64 min_size;

	if ((!size && !nr_nodes) \|\| (nr_nodes && !pblk))
	return -1;

	/*
	* In the 'uniform' case split the passed in physical node by
	* nr_nodes, in the non-uniform case, ignore the passed in
	* physical block and try to create nodes of at least size
	* @size.
	*
	* In the uniform case, split the nodes strictly by physical
	* capacity, i.e. ignore holes. In the non-uniform case account
	* for holes and treat @size as a minimum floor.
	*/
	if (!nr_nodes)
	nr_nodes = MAX_NUMNODES;
	else {
	nodes_clear(physnode_mask);
	node_set(pblk->nid, physnode_mask);
	uniform = 1;
	}

	if (uniform) {
	min_size = uniform_size(max_addr, addr, 0, nr_nodes);
	size = min_size;
	} else {
	/*
	* The limit on emulated nodes is MAX_NUMNODES, so the
	* size per node is increased accordingly if the
	* requested size is too small. This creates a uniform
	* distribution of node sizes across the entire machine
	* (but not necessarily over physical nodes).
	*/
	min_size = uniform_size(max_addr, addr,
	mem_hole_size(addr, max_addr), nr_nodes);
	}
	min_size = ALIGN(max(min_size, FAKE_NODE_MIN_SIZE), FAKE_NODE_MIN_SIZE);
	if (size < min_size) {
	pr_err("Fake node size %LuMB too small, increasing to %LuMB\n",
	size >> 20, min_size >> 20);
	size = min_size;
	}
	size = ALIGN_DOWN(size, FAKE_NODE_MIN_SIZE);

	/*
	* Fill physical nodes with fake nodes of size until there is no memory
	* left on any of them.
	*/
	while (!nodes_empty(physnode_mask)) {
	for_each_node_mask(i, physnode_mask) {
	u64 dma32_end = numa_emu_dma_end();
	u64 start, limit, end;
	int phys_blk;

	phys_blk = emu_find_memblk_by_nid(i, pi);
	if (phys_blk < 0) {
	node_clear(i, physnode_mask);
	continue;
	}

	start = pi->blk[phys_blk].start;
	limit = pi->blk[phys_blk].end;

	if (uniform)
	end = start + size;
	else
	end = find_end_of_node(start, limit, size);
	/*
	* If there won't be at least FAKE_NODE_MIN_SIZE of
	* non-reserved memory in ZONE_DMA32 for the next node,
	* this one must extend to the boundary.
	*/
	if (end < dma32_end && dma32_end - end -
	mem_hole_size(end, dma32_end) < FAKE_NODE_MIN_SIZE)
	end = dma32_end;

	/*
	* If there won't be enough non-reserved memory for the
	* next node, this one must extend to the end of the
	* physical node.
	*/
	if ((limit - end - mem_hole_size(end, limit) < size)
	&& !uniform)
	end = limit;

	ret = emu_setup_memblk(ei, pi, nid++ % MAX_NUMNODES,
	phys_blk,
	min(end, limit) - start);
	if (ret < 0)
	return ret;
	}
	}
	return nid;
	}

	static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
	struct numa_meminfo *pi,
	u64 addr, u64 max_addr, u64 size)
	{
	return split_nodes_size_interleave_uniform(ei, pi, addr, max_addr, size,
	0, NULL, 0);
	}

	static int __init setup_emu2phys_nid(int *dfl_phys_nid)
	{
	int i, max_emu_nid = 0;

	*dfl_phys_nid = NUMA_NO_NODE;
	for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++) {
	if (emu_nid_to_phys[i] != NUMA_NO_NODE) {
	max_emu_nid = i;
	if (*dfl_phys_nid == NUMA_NO_NODE)
	*dfl_phys_nid = emu_nid_to_phys[i];
	}
	}

	return max_emu_nid;
	}

	/**
	* numa_emulation - Emulate NUMA nodes
	* @numa_meminfo: NUMA configuration to massage
	* @numa_dist_cnt: The size of the physical NUMA distance table
	*
	* Emulate NUMA nodes according to the numa=fake kernel parameter.
	* @numa_meminfo contains the physical memory configuration and is modified
	* to reflect the emulated configuration on success. @numa_dist_cnt is
	* used to determine the size of the physical distance table.
	*
	* On success, the following modifications are made.
	*
	* - @numa_meminfo is updated to reflect the emulated nodes.
	*
	* - __apicid_to_node[] is updated such that APIC IDs are mapped to the
	* emulated nodes.
	*
	* - NUMA distance table is rebuilt to represent distances between emulated
	* nodes. The distances are determined considering how emulated nodes
	* are mapped to physical nodes and match the actual distances.
	*
	* - emu_nid_to_phys[] reflects how emulated nodes are mapped to physical
	* nodes. This is used by numa_add_cpu() and numa_remove_cpu().
	*
	* If emulation is not enabled or fails, emu_nid_to_phys[] is filled with
	* identity mapping and no other modification is made.
	*/
	void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
	{
	static struct numa_meminfo ei __initdata;
	static struct numa_meminfo pi __initdata;
	const u64 max_addr = PFN_PHYS(max_pfn);
	u8 *phys_dist = NULL;
	size_t phys_size = numa_dist_cnt * numa_dist_cnt * sizeof(phys_dist[0]);
	int max_emu_nid, dfl_phys_nid;
	int i, j, ret;

	if (!emu_cmdline)
	goto no_emu;

	memset(&ei, 0, sizeof(ei));
	pi = *numa_meminfo;

	for (i = 0; i < MAX_NUMNODES; i++)
	emu_nid_to_phys[i] = NUMA_NO_NODE;

	/*
	* If the numa=fake command-line contains a 'M' or 'G', it represents
	* the fixed node size. Otherwise, if it is just a single number N,
	* split the system RAM into N fake nodes.
	*/
	if (strchr(emu_cmdline, 'U')) {
	nodemask_t physnode_mask = numa_nodes_parsed;
	unsigned long n;
	int nid = 0;

	n = simple_strtoul(emu_cmdline, &emu_cmdline, 0);
	ret = -1;
	for_each_node_mask(i, physnode_mask) {
	/*
	* The reason we pass in blk[0] is due to
	* numa_remove_memblk_from() called by
	* emu_setup_memblk() will delete entry 0
	* and then move everything else up in the pi.blk
	* array. Therefore we should always be looking
	* at blk[0].
	*/
	ret = split_nodes_size_interleave_uniform(&ei, &pi,
	pi.blk[0].start, pi.blk[0].end, 0,
	n, &pi.blk[0], nid);
	if (ret < 0)
	break;
	if (ret < n) {
	pr_info("%s: phys: %d only got %d of %ld nodes, failing\n",
	__func__, i, ret, n);
	ret = -1;
	break;
	}
	nid = ret;
	}
	} else if (strchr(emu_cmdline, 'M') \|\| strchr(emu_cmdline, 'G')) {
	u64 size;

	size = memparse(emu_cmdline, &emu_cmdline);
	ret = split_nodes_size_interleave(&ei, &pi, 0, max_addr, size);
	} else {
	unsigned long n;

	n = simple_strtoul(emu_cmdline, &emu_cmdline, 0);
	ret = split_nodes_interleave(&ei, &pi, 0, max_addr, n);
	}
	if (*emu_cmdline == ':')
	emu_cmdline++;

	if (ret < 0)
	goto no_emu;

	if (numa_cleanup_meminfo(&ei) < 0) {
	pr_warn("NUMA: Warning: constructed meminfo invalid, disabling emulation\n");
	goto no_emu;
	}

	/* copy the physical distance table */
	if (numa_dist_cnt) {
	phys_dist = memblock_alloc(phys_size, PAGE_SIZE);
	if (!phys_dist) {
	pr_warn("NUMA: Warning: can't allocate copy of distance table, disabling emulation\n");
	goto no_emu;
	}

	for (i = 0; i < numa_dist_cnt; i++)
	for (j = 0; j < numa_dist_cnt; j++)
	phys_dist[i * numa_dist_cnt + j] =
	node_distance(i, j);
	}

	/*
	* Determine the max emulated nid and the default phys nid to use
	* for unmapped nodes.
	*/
	max_emu_nid = setup_emu2phys_nid(&dfl_phys_nid);

	/* commit */
	*numa_meminfo = ei;

	/* Make sure numa_nodes_parsed only contains emulated nodes */
	nodes_clear(numa_nodes_parsed);
	for (i = 0; i < ARRAY_SIZE(ei.blk); i++)
	if (ei.blk[i].start != ei.blk[i].end &&
	ei.blk[i].nid != NUMA_NO_NODE)
	node_set(ei.blk[i].nid, numa_nodes_parsed);

	numa_emu_update_cpu_to_node(emu_nid_to_phys, ARRAY_SIZE(emu_nid_to_phys));

	/* make sure all emulated nodes are mapped to a physical node */
	for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++)
	if (emu_nid_to_phys[i] == NUMA_NO_NODE)
	emu_nid_to_phys[i] = dfl_phys_nid;

	/* transform distance table */
	numa_reset_distance();
	for (i = 0; i < max_emu_nid + 1; i++) {
	for (j = 0; j < max_emu_nid + 1; j++) {
	int physi = emu_nid_to_phys[i];
	int physj = emu_nid_to_phys[j];
	int dist;

	if (get_option(&emu_cmdline, &dist) == 2)
	;
	else if (physi >= numa_dist_cnt \|\| physj >= numa_dist_cnt)
	dist = physi == physj ?
	LOCAL_DISTANCE : REMOTE_DISTANCE;
	else
	dist = phys_dist[physi * numa_dist_cnt + physj];

	numa_set_distance(i, j, dist);
	}
	}

	/* free the copied physical distance table */
	memblock_free(phys_dist, phys_size);
	return;

	no_emu:
	/* No emulation. Build identity emu_nid_to_phys[] for numa_add_cpu() */
	for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++)
	emu_nid_to_phys[i] = i;
	}

	#ifndef CONFIG_DEBUG_PER_CPU_MAPS
	void numa_add_cpu(unsigned int cpu)
	{
	int physnid, nid;

	nid = early_cpu_to_node(cpu);
	BUG_ON(nid == NUMA_NO_NODE \|\| !node_online(nid));

	physnid = emu_nid_to_phys[nid];

	/*
	* Map the cpu to each emulated node that is allocated on the physical
	* node of the cpu's apic id.
	*/
	for_each_online_node(nid)
	if (emu_nid_to_phys[nid] == physnid)
	cpumask_set_cpu(cpu, node_to_cpumask_map[nid]);
	}

	void numa_remove_cpu(unsigned int cpu)
	{
	int i;

	for_each_online_node(i)
	cpumask_clear_cpu(cpu, node_to_cpumask_map[i]);
	}
	#else /* !CONFIG_DEBUG_PER_CPU_MAPS */
	static void numa_set_cpumask(unsigned int cpu, bool enable)
	{
	int nid, physnid;

	nid = early_cpu_to_node(cpu);
	if (nid == NUMA_NO_NODE) {
	/* early_cpu_to_node() already emits a warning and trace */
	return;
	}

	physnid = emu_nid_to_phys[nid];

	for_each_online_node(nid) {
	if (emu_nid_to_phys[nid] != physnid)
	continue;

	debug_cpumask_set_cpu(cpu, nid, enable);
	}
	}

	void numa_add_cpu(unsigned int cpu)
	{
	numa_set_cpumask(cpu, true);
	}

	void numa_remove_cpu(unsigned int cpu)
	{
	numa_set_cpumask(cpu, false);
	}
	#endif /* !CONFIG_DEBUG_PER_CPU_MAPS */